Electron devices with planar electrodes,and means for terminating transmission lines with same



July 22, 1969 ELECTRON DEVICES WITH PLANAR ELECTRODES, AND MEANS FOR TERMINATING TRANSMISSION LINES WITH SAME Original Filed April 1. 1960 FIGJ .Laca/ D. M. GOODMAN Directional Coupler Band Mixer My 1 f I l 41f 40a 0 44- --/414 I 7 5 442 #6 H I i 432 F- F i 4? l! u FIG. 2A 420 1 1 1 1 4770 212 Y/\\/ FIG. 4 /409 Dl'n'clmrm/ 415 27 Coup/er r 41 2 local 42 dull/afar 97 INVENTOR 52 222 gggg g/ David M 600 man J @255 3:5 fl/ Mc xer Mixer TTORNE United States Patent 3,457,515 ELECTRON DEVICES WKTH PLANAR ELEC- TRODES, AND MEANS FOR TERMINATING TRANSMISSION LINES WITH SAME David M. Goodman, 3843 Debra Court, Seaford, NY. 11783 Continuation of application Ser. No. 19,355, Apr. 1, 1960, which is a continuation-in-part of application Ser. No. 485,001, Jan. 31, 1955. This application June 28, 1965,

Ser. No. 467,424

Int. Cl. H041) 1/18 U.S. Cl. 325-445 14 Claims ABSTRACT 0F THE DISCLOSURE This application is a continuation of my pending application Ser. No. 19,355 filed Apr. 1, 1960 and now abandoned which in turn was a continuation-in-part of my application Ser. No. 485,001 filed Ian. 31, 1955, now U.S. Patent 2,931,900. That invention (2,931,900) relates to the study of steady state, transient, linear, and non-linear electrical parameters and phenomena. In particular, that invention is directed to means for measuring the relationship of two or more quantities in an electrical system. It is directed to making sweep frequency measurements of incident and reflected voltage in transmission lines, Nyquist polar diagrams, gain-phase plots, loss-phase plots, etc. This invention is directed towards a sub-combination of that invention. In particular, this invention relates to electron tubes and electron tube circuits which are capable of operating with uniform behavior over an extended frequency range.

Accordingly, the primary object of this invention is to improve upon the large bandwidth handling capability of planar type electron discharge devices.

Another object of this invention is to provide circuit means for taking advantage of the larbe bandwith handling capability provided by planar type electron discharge devices.

Further objects and advantages of this invention will become apparent from the following description of the invention taken in conjunction with the accompanying drawing wherein:

FIGURE 1 is a block diagram showing a basic embodiment of this invention in which two broad-band mixers operate over a substantial frequency range.

FIGURE 2 is a diagrammatic illustration of one of the broad-band mixers of FIGURE 1. Part of a triode mixer and a three step coaxial transmission line are shown in cross-section. Part of the electrical circuitry is also shown.

FIGURE 2A is a magnified view of a portion of the triode illustrated in FIGURE 2.

FIGURE 3 is a simplified electrical schematic diagram of the triode shown in cross-section in FIGURES 2 and 2A.

Patented July 22, 1969 FIGURE 4, which is akin to FIGURE 1, is a block diagram showing another arrangement which makes use of the broad-band mixers of FIGURES 2 and 3.

FIGURE 1 illustrates a heterodyne system employing two mixers which operate over the frequency range 400- 1600 me. Two signals in this frequency range are derived from directional coupler 212. For descriptive details on a system in which this configuration of a directional coupler may be deployed, reference is made to the parent U.S. Patent 2,931,900 mentioned above. For the purposes at hand, however, it will suffice to state that the two signals which are to be compared are derived from the di rectional coupler. Typically, one signal is proportional to the incident voltage, the other signal proportional to the reflected voltage on the transmission line to which the coupler is connected. One of the two signals is transmitted through a 50 ohm cable 216, through a coaxial terminated in the internal impedance of a grounded grid '1 400, to a three step coaxial transition 404 which is Western Electric Type 416A or Western Electric Type 416B triode contained in broad-band mixer 220. In like manner the other signal is transmitted through 50 ohms cable 218, through a coaxial T 402, to a three step coaxial transition 406 which is terminated in the internal impedance of a second grounded grid broad-band mixer 222. Simultaneously the local oscillator 287, feeds a coaxial T 458, which in turn feeds pads 454, and 456. The local oscillator signal that emerges from pad 454 passes via coaxial cable to T 402 and thence to mixer 222. At the same time the local oscillator signal that emerges from pad 456 passes via coaxial cable to T 400 and thence to mixer 220. The T 458 is balanced. The pads 454 and 456, and the TS 400 and 402 are matched in both ampli tude and phase behavior in the frequency range under consideration. Similarly the broad-band mixers 220 and 222 (alike in construction) are matched.

FIGURE 2 diagrammatically shows the broad-band mixer 220 and part of transition 404, in detail. The Westtern Electric Type 416 vacuum tube planar triode is designated by 407. The triode elements are identified as heater 405, cathode 412, grid member 417, and plate member 420. The end of the three step transition 404 that connects to the planar triode is shown by the dashed lines. The outer conductor 418 of the transition 404 is shown connected to the terminal ring of the grid member 417; the inner conductor 424 is shown connected to the cathode shell 426. Between cathode shell 426 and the cathode 417 is coupling capacitor 422, an element of triode 407.

The circuit connections to the heater 405 include chokes 430 and 432, and bypass capacitors 434, 436, 438, 440 and 442; the lead-in connections are designated 408 and 410. The circuit connections to the cathode 412. include choke 428, bypass capacitors 444, fixed tuning capacitor 446, variable trimmer 448, choke 450, and the cathode bias resistor 452; the lead-in connection is designated 414.

Referring back to FIGURE 1 temporarily, it is seen that the voltage from one arm of the directional coupler 212 and the injection voltage from the local oscillator 287 are combined in coaxial T 400 for transmission to the broad-band mixer 220. Typically, the output of T 400 is transmitted via coaxial cable. Since the structure and dimensions of this cable are different from planar triode 407 of mixer 220, a coupling transition is provided. The design of this transition for the instant invention yielded a three step unit which is outlined at 404 in FIGURE 1, and partially detailed in FIGURE 2. In the latter figure, the two incoming voltages are transmitted in the transition via elements 458 and 460 to elements 424 and 418, respectively. Via these last two elements and coupling capacitor 422, the signals are impressed between the grid and cathode of the triode.

The schematic diagram of FIGURE 2 is illustrated in FIGURE 3 where elements akin to those in FIGURE 2 bear the same numbers. The incoming signals are fed in at 462 for transmission through coupling capacitor 422 to the cathode 412. The grid 417 is grounded at 418. The output emerges from plate 420. Connections 408 and 410 introduce heater voltage to heater element 405; connection 414 provides the direct current bias for the tube. As stated before, the tube employed in the instant invention is a Western Electric Type 416. The cathode, grid, and plate elements are plane and parallel to each other as illustrated in FIGURE 2. The plate terminates in a member 420; the grid terminates in a ring-like connector 417a. The cathode terminal is a cylindrical sleeve 426. The resonant frequency of the tube is approximately 4000 mc. The triode is operated as a grounded grid mixer. The signal levels of both the local oscillator and the other input voltage are of low order of magnitude to make the conversion through the 416 triode a linear process, both amplitude and phase-wise. The operational properties of the two mixers 220 and 222 are established so that the functional behavior of the two mixers is identical over the frequency range 400-1600 mc.

An alternative to the means illustrated in FIGURE 1 for local oscillator injection is shown in FIGURE 4. The signal supplied by 287 feeds symmetrical T 504 which in turn feeds two directional couplers 500 and 502. Coupler 500 combines the signal from the incident arm of the directional coupler 212 with the signal from 287, both of which are fed to mixer 220. Coupler 502 combines the signal from the reflected arm of the coupler 212 with the signal from 287, both of which are fed to the mixer 222. The two couplers 500 and 502 have similar characteristics. When the broad-band mixers 220 and 222 represent a matched load to input signals, the isolation between channels becomes a function of the coupling factor and directively of the couplers 500 and 502. The resultant combination minimizes the signal losses while maximizing the isolation between mixers 220 and 222. In connection with this last-mentioned alternative, it is noted by referring to FIGURES 2 and 3 that the input circuits of broad-band mixers 220 and 222 operate untuned. Depending upon the center frequency and the frequency range to be covered it may be desirable to tune the input capacity of the mixers used. This results in improved elfective signal strengths. With the injection means shown in FIGURE 4, this tuning also improves the isolation between channels.

It has been stated that the mixers 220 and 222 ar fed by transitions 404 and 406 respectively. These coaxial line transitions are terminated by the internal impedance of the mixers. In these grounded grid mixers the input impedance is approximately 1/ gm; with a transconductance of 20,000 micromhos the internal impedance is approximately 50 ohms. Accordingly, cathode resistor 452 and the plate voltage applied to 420 are selected to match the input impedance of the tube to the transition sections. Resistive element 415, shown in FIGURES 2 and 3, also may be used to match the tube to the transmission line.

Resistor '415 is of annular construction and is located between grid 417 and cathode 412 of tube 407, as illustrated in FIGURE 3, thereby becoming a part of the tube. In FIGURE 2, resistor 415 is shown disposed between the grid terminal ring 417a and the cathode shell 426. This is also shown in FIGURE 2A which magnifies a portion of FIGURE 2. When the resistor is disposed within the envelope of the tube, as illustrated in FIG- URE 2A, it may be coated with glass. Also ceramic film resistors may be used. The purpose of course is to have resistor 415 adjacent to or integral with insulator 409. In both FIGURES 2 and 2A, the grid 417 of tube 407 is connected to terminal ring 417a; the cathode 412 is connected via capacitor 422 to cathode shell 426; the plate 420 is insulated from grid terminal 4170 by spider 421; and the cathode shell 426 is insulated from the grid terminal 417a by cylinder 409. Resistor 415 is adjacent insulator 409. The value of resistive element 415 is preselected depending upon the geometry of the transition, the mode of operation of the tube, and the voltage connected thereto. This arrangement eliminates the need for tuning the input capacitance when the line impedance is low, and provides a match of tube to transmission line which substantially improves the broad band characteristics of the mixers 220 and 222.

In FIGURE 2 chokes 428 and 450 and tuning capacitors 444, 446 and 448 operate to reduce the cathode impedance of the mixers 220 and 222 to the 21 mc. output signal of said mixers. It is also to be noted that chokes 428, 430 and 432 may be placed within the inner conductor of the transmission line step transition. The transition need not be a three step, need not be abrupt, and may be constructed for different line impedances. These variations depend upon the frequency range under consideration. In fact, at the lower frequencies the coaxial construction may be replaced by conventional line connections and wiring, and the directional couplers themselves may be replaced by Wheatstone bridge circuits. Additionally, at the lower frequencies each of the mixers may operate push-pull with attendant improvement in performance and rejection of local oscillator signal.

It is to be noted that the particular embodiments of the invention illustrated and described herein are illustrative only, and the invention includes such other modifications and equivalents as may appear obvious to those skilled in this art. Therefore, it should be appreciated that although the invention is described and illustrated as it applies to the Type 416 receiving type vacuum tube, the structure and techniques herein disclosed can also be applied directly to gas filled electron discharge devices and to transmitting type electron discharge devices. Moreover, since the spacing between the active elements in the discharge device can be varied over a wide range of dimensions, these teachings can be app-lied equally successfully to various semi-conductor devices so long as the elements contained therein equivalent to the electrodes illustrated in FIGURE 2 are physically arranged to be plane and parallel to each other.

Thus, having described my invention and some of the uses to which it may be put I claim:

1. An electron discharge device comprising: a cathode electrode, a control grid electrode, and a plate electrode, wherein the portions of said electrodes which control the passage of electrons from the cathode to the plate are substantially plane and parallel; an insulating memher which separates said cathode from said grid; a resistive element connected permanently in circuit between said cathode and said grid electrodes; and wherein said insulating member and said resistive element are in juxtaposition.

2. A vacuum tube comprising: a cathode electrode, a control grid electrode, and a plate electrode, wherein the portions of said electrodes which control the passage of electrons from the cathode to the plate are substtantially plane and parallel; an insulating member of annular shape which separates said cathode from said grid; and a resistive element adhered to said insulating member which provides a circuit between said cathode and grid electrodes.

3. The vacuum tube of claim 2 wherein the resistive elebment is located within the evacuated portion of the to e.

4. A vacuum tube comprising: a cathode electrode, a control grid electrode, and a plate electrode, wherein the portions of said electrodes which control the passage of electrons from the cathode to the plate are substantially plane and parallel; a cathode electrode contact ring; a grid electrode contact ring; an insulating member which separates said contact rings, and which supports the grid and cathode electrodes and which provides a vacuum seal; and an annular resistive element located on the interior side of said insulating member for providing a resistive termination permanently in circult between the cathode and grid electrodes.

5. A vacuum tube circuit comprising: a vacuum tube having a plurality of electrodes for controlling the passage of electrons therebetween wherein the portions of the electrodes which control the electron flow are substantially plane and parallel, including a cathode electrode and a grid electrode, each electrode having a ring-like member for making electrical contact therewith, and a plate elec trode; an input transmission line having an inner and outer coaxial conductor; a transition coupling which connects said inner coaxial conductor to the ring-like cathode electrode and said outer coaxial conductor to the ring-like grid electrode; and a transmission line terminating resistor located adjacent to and making electrical connection with said ring-like members of the cathode and grid electrodes.

6. The circuit of claim 5 wherein said terminating resistor is annular in shape and positioned between the ring-like members of the cathode and grid electrodes.

7. A grounded grid vacuum tube circuit comprising: a vacuum tube having a plurality of electrodes for controlling the passage of electrons therebetween wherein the portions of the electrodes which control the electron flow are substantially plane and parallel, including a cathode electrode and a grid electrode, each electrode having a ring-like member for making electrical contact therewith, and a plate electrode; an input transmission line having an inner and outer coaxial conductor; a transition coupling which connects said inner coaxial conductor to the ring-like cathode electrode and said outer coaxial conductor to the ring-like grid electrode; and electrical circuit means for providing electrode voltages which control the transconductance of the tube in order to adjust the input impedance, between cathode and grid, of the vacuum tube to provide a matched load for the transmission line.

8. A vacuum tube grounded grid mixer circuit comprising: a vacuum tube having a plurality of electrodes for controlling the passage of electrons therebetween wherein the portions of the electrodes which control the electron flow are substantially plane and parallel, including a cathode electrode and a grid electrode, each electrode having a ring-like member for making electrical contact therewith, and a plate electrode; an input transmission line having an inner and outer coaxial conductor for introducing two different signals; a transition coupling which connects said inner conductor to the ring-like cathode electrode and said outer conductor to the ring-like grid electrode, said outer conductor adapted to be grounded; means to assist in terminating the transmission line comprising a resistor located adjacent to and making electrical connection with the ring-like members of the cathode and grid electrodes; and means connected to said plate for filtering and for carrying away an output signal derived from the mixing action in the tube.

9. The circuit of claim 8 wherein said terminating resistor is annular in shape.

10. An electron discharge device comprising: a cathode electrode, a control grid electrode, and a plate electrode, wherein the portions of said electrodes which control the passage of electrons from the cathode to the plate are substantially plane and parallel; a cathode electrode contact ring; a grid electrode contact ring; an insulating member which separates said contact rings, and which supports the grid and cathode electrodes and which provides a vacuum seal; and an annular resistive element located permanently on the exterior side of said insulating member for providing a resistive termination between said cathode and grid electrodes.

11. A termination for a coaxial transmission line comprising: an electron discharge device having (1) electrodes with active areas which are plane and parallel, and (2) ring-like terminals for making electrical connections from a first and second of said electrodes to the inner and outer conductor of said coaixial line respectively, and (3) resistive means adjacent said ring-like electrodes and permanently secured thereto, said last means having a resistance value substantially equal to the characteristic impedance of the coaxial transmission line.

12. A termination for a coaxial transmission line comprising a coaxial transition element with one end thereof connected to said coaxial line and with the other end of said transition connected to an energizable electron discharge device, said device having (1) electrodes with active areas which are plane and parallel, and (2) ringlike terminals for making electrical connections from a first and second of said electrodes to the inner and outer conductor of said transition element, respectively, and (3) circuit connections for energizing said discharge device whereby the input impedance thereof provides said coaxial transmission line with a resistive termination substantially equal to its characteristic impedance.

13. The combination of claim 12 wherein the input impedance of the discharge device is approximately 50 ohms.

14. The combination of claim 12 wherein the inner conductor of said transition element is hollow and wherein circuitc onnecting leads pass through the hollow region of said transition element.

No References Cited.

KATHLEEN H. CLAFFY, Primary Examiner R. S. BELL, Assistant Examiner US. Cl. X.R. 

